How big were nesting colonies?

Dinosaurs like the Maiasaurus lived in huge herds, probably containing many thousands of individuals. Their breeding colonies were probably also very large. Their nests were placed about 7 m apart, which is roughly the length of an adult Maiasaurus.

This arrangement allowed the dinosaurs to crowd together without getting in each other's way.

These great nesting sites gave some protection from predators. Also, by grouping the young together it was relatively easy for the parent to find its own offspring after going off to forage for food.